I actually just purchased a "cheap" cai as well.. They are all the same.. Basically 2.75 - 3" tubing with a reusable filter. As mentioned, just look for the maf adapter port and make sure the company has at least a return/exchange policy you can agree with in case they send something different. BCP 03-08 Mazda6 S 3.0 3.0L V6 Cold Air Intake + Filter - eBay (item 140510758029 end time Feb-16-11 17:31:34 PST) is what I got. Should be in for me this tuesday. I am going to swap the filter for a K&N and I will be purchasing some thermal wrapping for it as well.. 
The BEST mods may be the most expensive, but that doesn't mean the most expensive mod is best for you
The BEST mods may be the most expensive, but that doesn't mean the most expensive mod is best for you
